geothermal resource potential of the safford-san simon basin, arizona

silt.
These deposits become more coarse-grained as the mountain front is
approached.
Drillers' well logs are interpreted to show sands and gravels
interfingering in the clay and siltstone.
The thermal artesian aquifers in
the area are believed to be sand and gravel tongues in the green clay facies
of Harbour (1966).
Medium- to coarse-grained and weakly stratified sands resmbling grus
overlie the green clay facies west of Artesia.
Thin, discontinuous lenses
of cobble to boulder conglomerate occur in these sediments, which are correlated
with Harbour's pediment facies.
are in contact with'weathered bedrock.
West of Metate Peak, these sediments
Here, the highly weathered gneiss
resembles a red saprolite; the feldspars are mostly altered to red clay.
The foliation and augen texture of the gneiss is distinguishable and facilitates
definition of the contact with the overlying basin fill.
Basin fill
at Metate Peak is unusually fine-grained considering its position next to
the mountain front. However, above these basin-fill sediments, several dissected
deposits of boulder conglomerate consisting of weathered gneiss boulders
occur in the mouths of canyons.
It is inferred that these deposits
mostly overlie the pediment facies and are remnants of fans.
A gross climatic
change may be indicated in the change from grus like fan deposits next to the
mountain front to the overlying boulder fanglomerate.
In any case, it appears
that all of these sediments are hydrologically connected and they allow the
recharge of water to the gravel and sand tongues in the green clay facies and
an inferred, deep, basal conglomerate below the clay deposits.
The area's subsurface structure and stratigraphy is further defined by
geophysical data.
Both gravity and aeromagnetic data (Wynn and Dansereau,
1979; Sauck and Sumner, 1970) show steep gradients between U.S. Highway 666
and the Pinaleno Mountain front (Figures 16 and 17). The steep gradients
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